1. Field of the Invention
The present invention relates to a gain controlling apparatus and a gain controlling method, an information reproducing apparatus having the gain controlling apparatus and an information reproducing method having the gain controlling method, and an information recording apparatus having the gain controlling apparatus and an information recording method having the gain controlling method. More particularly, the present invention relates to a gain controlling apparatus for controlling a gain of a signal used for a reproducing control or a recording control when at least one of an information reproducing operation and an information recording operation is optically carried out from and onto an information recording medium such as an optical disc and the like, and a gain controlling method for controlling it, an information reproducing apparatus having the gain controlling apparatus and an information reproducing method having the gain controlling method, and an information recording apparatus having the gain controlling apparatus and an information recording method having the gain controlling method.
2. Description of the Related Art
Conventionally, if information is optically reproduced or recorded as mentioned above, a light beam, such as a laser light for the reproduction or the record and the like, is irradiated onto an information recording medium such as an optical disc or the like, and then a signal generated by receiving its reflection light is used to usually carry out various controls or reproducing processes or recording processes.
More concretely, the conventional information reproducing apparatus or information recording apparatus has the following configuration. For example, a light detection signal generated by receiving the reflection light is processed to generate a so-called focus error signal (namely, a focus error signal indicative of a deviation in a direction perpendicular to an information recording medium at a focal position of a light beam) or a tracking error signal (namely, a tracking error signal indicative of a deviation in a direction parallel to the information recording medium at a focal point of a light beam). Based on this, the focal point is servo-controlled in the perpendicular or parallel direction to accurately reproduce or record the information.
In this case, the respective servo controls are carried out by optimizing a gain (or a sensibility) in the focus error signal or the tracking error signal in response to a strength of the obtained reflection light. Here, the reason why the gain is optimized is that the extremely high gains of the respective error signals may cause the mechanism of the servo control to oscillate in the worst case. Thus, the servo control cannot be carried out. On the other hand, the extremely low gains may disable the respective error signals to function as the error signals.
Even if the information is reproduced on the basis of a reproduction signal generated by receiving the reflection light (actually, on the basis of a reproduction RF (Radio Frequency) signal corresponding to the information recorded on an information recording medium and the like), it is usual to adjust a gain of the reproduction signal so as to be suitable for the reproducing process.
For example, if the contamination of the surface of an objective lens within an optical pickup and the like causes the strength of the light detection signal generated by the reception of the reflection light to be reduced in conjunction with a temporal elapse, the above-mentioned gain adjustment is required to compensate the drop of the gain of the reproduction signal resulting from the reduction of the strength.
Conventionally, in order to mainly shorten the adjustment times, as for the above-mentioned adjustments of the gains of the respective signals, a rough adjustment (this actually implies an adjustment using a rough adjustment unit over a wide gain range, and this is hereafter used in the same meaning) is transiently performed on the gains of the respective input signals. Based on the result of this rough adjustment, a fine adjustment (this actually implies an adjustment that a gain after the rough adjustment is adjusted by using a carefully thought out adjustment unit as compared with an adjustment unit of the rough adjustment, with regard to a range of a gain which contains the gain after the rough adjustment and is narrower than a range of a gain of the rough adjustment) is further carried out to accordingly obtain an adjusted value of a desired gain for each signal.
Here, the rough and fine adjustments are further actually described. For example, supposing that in one signal a range of a gain to be finely adjusted is a range of xc2x16 dB, if a value of a gain after the fine adjustment is greater than +6 dB with respect to an initial value of the gain of the one signal, it is determined that a gain control in the rough adjustment immediately before is not adequate. At a next gain adjustment timing, the gain is increased in advance by +6 dB with respect to the initial value of the gain at a time of the rough adjustment. In the fine adjustment after that, the fine adjustment is repeated in the range of xc2x16 dB.
When as for the one signal, a range of a gain to be finely adjusted is similarly assumed to be xc2x16 dB, if a value of the gain after the fine adjustment is lower than xe2x88x926 dB with respect to the initial value of the gain of the one signal, it is determined that the gain control in the rough adjustment immediately before is not similarly adequate. At a next gain adjustment timing, the gain is decreased in advance by xe2x88x926 dB with respect to the initial value of the gain in the rough adjustment. In the fine adjustment after that, the fine adjustment is repeated in the range of xc2x16 dB.
However, in a case of the adjusting method composed of the combination of the above-mentioned rough and fine adjustments, whenever the rough adjustment is once carried out, it is always necessary to use its result to accordingly carry out the fine adjustment. This implies that if an adjusted value in the rough adjustment is frequently changed at a minor temporal interval, the fine adjustment is repeated in conjunction with the change. This results in an increase of the entire adjustment time duration, which brings about a problem that it takes a wasteful time to proceed to a next process (namely, an actual reproducing or recording process, or the like).
On the other hand, if the number of rough adjustments is reduced by widening the adjustment range in the rough adjustment so as to solve this problem, it takes a long time to carry out the fine adjustment associated with the reduction (namely, the reduction of the number of rough adjustments brings about the expansion of a range of a gain to be finely adjusted. Thus, the time duration required for the fine adjustment is increased). This results in a problem that a time as the entire adjustment time duration is not shorten.
The present invention is proposed in view of the above mentioned problems. It is therefore an object of the present invention to provide a gain controlling apparatus and method, an information reproducing apparatus and method and an information recording apparatus and method, which can shorten a gain adjustment time duration without dropping the adjustment accuracy.
The above object of the present invention can be achieved by a gain controlling apparatus provided with: a roughly adjusting device such as a pre-amplifier or the like for roughly adjusting a gain of a generation signal, which is generated on the basis of a light detection signal obtained by receiving a reflection light of a light beam from an information recording medium such as an optical disc or the like; a finely adjusting device such as a variable amplifier or the like for finely adjusting the gain on the basis of a result of roughly adjusting the gain by the roughly adjusting device; a memory device such as a memory or the like for storing a plurality of values of the generation signal generated until a previous occasion of gain adjustment in time series; and a controlling device such as a CPU or the like for controlling the roughly adjusting device to roughly adjusting the gain at a current occasion of gain adjustment on the basis of the respective stored values of the generation signal and also controlling the finely adjusting device to finely adjust the gain on the basis of a result of roughly adjusting the gain at the current occasion by the roughly adjusting device.
According to the gain controlling apparatus of the present invention, at first, the gain at the current occasion is roughly adjusted by the roughly adjusting device, on the basis of the respective stored values of the generation signal. Then, the gain is finely adjusted by the finely adjusting device, on the basis of a result of the rough adjustment of the gain at the current occasion. Thus, it is possible to roughly adjust the gain with predicting the change in the value of the generation signal in advance, followed by the fine adjustment. Accordingly, such a possibility is increased that the adjustment value at the previous occasion can be used as it is for the rough adjustment at the current occasion, followed by the fine adjustment. Consequently, it is possible to effectively prevent the increase of the time duration required for the gain adjustment due to a frequent change of the rough adjustment value for each occasion of the rough adjustment, while keeping the adjustment accuracy high.
In this manner, in case of reproducing or recording the information from or onto the information recording medium, it is possible to prevent the increase of the time duration required for the gain adjustment, and reproduce or record the information precisely and speedily.
In one aspect of the gain controlling apparatus of the present invention, the controlling device is provided with a predicting device such as a CPU or the like for predicting a current adjustment value, which is an adjusted value for the gain roughly adjusted at the current occasion by the roughly adjusting device. The controlling device controls the roughly adjusting device to roughly adjust the gain at the current occasion on the basis of the predicted current adjustment value.
According to this aspect, since the current adjustment value is predicted by using the values of the generation signal at the past occasions, which are accumulated in time series in the memory, and since the gain is roughly adjusted on the basis of this predicted value, it is possible to effectively prevent the increase of the time duration required for the gain adjustment while keeping the adjustment accuracy high.
In this aspect of having the predicting device, the current adjustment value may be predicted when adjusting the gain at the previous occasion.
By constructing in this way, since the rough adjustment at the current occasion is performed by using the current adjustment value which was predicted and set at the previous occasion, it is not necessary to newly set the adjustment value at the current occasion. Consequently, it is possible to further shorten the time duration required for the gain control at the current occasion.
In this aspect of having the predicting device, the gain may be changed in conjunction with a change of a characteristic of the reflection light. The predicting device may be provided with: a correlation parameter generating device such as a CPU or the like for generating a correlation parameter having a correlation with the reflection light by using a correlation generation signal, which is the generation signal having a characteristic correlated with the characteristic of the reflection light; and a change parameter generating device such as a CPU or the like for generating a change parameter indicative of an aged change of the characteristic of the reflection light by using each correlation parameter corresponding to the respective one of the stored values of the generation signal. The predicting device may predict the current adjustment value for the gain, on the basis of the generated change parameter.
By constructing in this way, since the current adjustment value is predicted while generating the correlation parameter and the change parameter respectively, it is possible to predict the current adjustment value more precisely and prevent the increase of the time duration required for the gain control in conjunction with the change in the characteristic of the reflection light.
In this case, the information recording medium may be recorded with information by forming a record track. The correlation generation signal may be at least one of a detection signal corresponding to the information and an error signal indicative of a deviation from the record track at an irradiation position of the light beam on the information recording medium.
By constructing in this way, since the correlation parameter and the change parameter are generated on the basis of the detection signal and/or the error signal, each having a strong correlation with the reflection light, it is possible to more precisely grasp the change in the gain to be adjusted due to the aged change in the characteristic of the reflection light, to thereby adjust the gain.
In this case further, the information recording medium may be shaped in a disc, and the error signal may be at least one of a tracking error-signal indicative of a deviation from the record track in a radial direction of the information recording medium at the irradiation position and a focus error signal indicative of a deviation from the record track in a direction perpendicular to the information recording medium at the irradiation position.
By constructing in this way, in case of reproducing or recording the information from or onto the information recording medium shaped in a disc e.g., an optical disc, it is possible to more precisely grasp the change in the gain to be adjusted due to the aged change in the characteristic of the reflection light, to thereby adjust the gain.
Alternatively in this case further, the information recording medium may be shaped in a disc, and the error signal may be at least one of (i) a first gain signal which indicates a gain in a tracking servo control using a tracking error signal indicative of a deviation from the record track in a radial direction of the information recording medium at the irradiation position and (ii) a second gain signal which indicates a gain in a focus servo control using a focus error signal indicative of a deviation from the record track in a direction perpendicular to the information recording medium at the irradiation position.
By constructing in this way, in case of reproducing or recording the information from or onto the information recording medium shaped in a disc e.g., an optical disc, it is possible to more precisely grasp the change in the gain to be adjusted due to the aged change in the characteristic of the reflection light, to thereby adjust the gain.
The above object of the present invention can be also achieved by an information reproducing apparatus provided with (i) the above described gain controlling apparatus of the present invention (including its various aspects), (ii) an optical pickup device such as an optical pickup or the like for irradiating the light beam onto the information recording medium and receiving the reflection light to thereby output the light detection signal, (iii) a signal generating device such as an adder or the like for generating the generation signal on the basis of the light detection signal outputted from the optical pickup device, and (iv) a reproduction controlling device such as a CPU or the like for controlling a reproduction of the information in accordance with the generation signal, the gain of which is roughly and finely adjusted.
According to the information reproducing apparatus of the present invention, it is possible to speedily reproduce the information from the information recording medium while shortening the time duration required for the gain control for the generation signal.
The above object of the present invention can be also achieved by an information recording apparatus provided with (i) the above described gain controlling apparatus of the present invention (including its various aspects), (ii) an optical pickup device such as an optical pickup or the like for irradiating the light beam onto the information recording medium and receiving the reflection light to thereby output the light detection signal, (iii) a signal generating device such as an adder or the like for generating the generation signal on the basis of the light detection signal outputted by the optical pickup device, (iv) a reproducing device such as a DSP (Digital Signal Processor) or the like for reproducing the information from the information recording medium on the basis of the generation signal, the gain of which is roughly and finely adjusted, and (v) a recording device such as an encoder or the like for processing record information, which is to be recorded onto the information recording medium, on the basis of the reproduced information and recording the processed record information onto the information recording medium.
According to the information recording apparatus of the present invention, it is possible to speedily record the information onto the information recording medium while shortening the time duration required for the gain control for the generation signal.
The above object of the present invention can be also achieved by a gain controlling method including: a roughly adjusting process of roughly adjusting a gain of a generation signal, which is generated on the basis of a light detection signal obtained by receiving a reflection light of a light beam from an information recording medium such as an optical disc or the like; a finely adjusting process of finely adjusting the gain on the basis of a result of roughly adjusting the gain by the roughly adjusting process; a storing process of storing into a memory device a plurality of values of the generation signal generated until a previous occasion of gain adjustment in time series; and a controlling process of controlling the roughly adjusting process to roughly adjusting the gain at a current occasion of gain adjustment on the basis of the respective stored values of the generation signal and also controlling the finely adjusting process to finely adjust the gain on the basis of a result of roughly adjusting the gain at the current occasion by the roughly adjusting process.
According to the gain controlling method of the present invention, at first, the gain at the current occasion is roughly adjusted by the roughly adjusting process, on the basis of the respective stored values of the generation signal. Then, the gain is finely adjusted by the finely adjusting process, on the basis of a result of the rough adjustment of the gain at the current occasion. Thus, it is possible to roughly adjust the gain with predicting the change in the value of the generation signal in advance, followed by the fine adjustment. Accordingly, such a possibility is increased that the adjustment value at the previous occasion can be used as it is for the rough adjustment at the current occasion, followed by the fine adjustment. Consequently, it is possible to effectively prevent the increase of the time duration required for the gain adjustment due to a frequent change of the rough adjustment value for each occasion of the rough adjustment, while keeping the adjustment accuracy high.
In this manner, in case of reproducing or recording the information from or onto the information recording medium, it is possible to prevent the increase of the time duration required for the gain adjustment, and reproduce or record the information precisely and speedily.
In one aspect of the gain controlling method of the present invention, the controlling process includes a predicting process of predicting a current adjustment value, which is an adjusted value for the gain roughly adjusted at the current occasion by the roughly adjusting process, and the controlling process controls the roughly adjusting process to roughly adjust the gain at the current occasion on the basis of the predicted current adjustment value.
According to this aspect, since the current adjustment value is predicted by using the values of the generation signal at the past occasions, which are accumulated in time series in the memory, and since the gain is roughly adjusted on the basis of this predicted value, it is possible to effectively prevent the increase of the time duration required for the gain adjustment while keeping the adjustment accuracy high.
In this aspect of having the predicting process, the current adjustment value may be predicted when adjusting the gain at the previous occasion.
By constructing in this way, since the rough adjustment at the current occasion is performed by using the current adjustment value which was predicted and set at the previous occasion, it is not necessary to newly set the adjustment value at the current occasion. Consequently, it is possible to further shorten the time duration required for the gain control at the current occasion.
In this aspect of having the predicting process, the gain may be changed in conjunction with a change of a characteristic of the reflection light. The predicting process may include: a correlation parameter generating process of generating a correlation parameter having a correlation with the reflection light by using a correlation generation signal, which is the generation signal having a characteristic correlated with the characteristic of the reflection light; and a change parameter generating process of generating a change parameter indicative of an aged change of the characteristic of the reflection light by using each correlation parameter corresponding to the respective one of the stored values of the generation signal. The predicting process may predict the current adjustment value for the gain, on the basis of the generated change parameter.
By constructing in this way, since the current adjustment value is predicted while generating the correlation parameter and the change parameter respectively, it is possible to predict the current adjustment value more precisely and prevent the increase of the time duration required for the gain control in conjunction with the change in the characteristic of the reflection light.
In this case, the information recording medium may be recorded with information by forming a record track; and the correlation generation signal is at least one of a detection signal corresponding to the information and an error signal indicative of a deviation from the record track at an irradiation position of the light beam on the information recording medium.
By constructing in this way, since the correlation parameter and the change parameter are generated on the basis of the detection signal and/or the error signal, each having a strong correlation with the reflection light, it is possible to more precisely grasp the change in the gain to be adjusted due to the aged change in the characteristic of the reflection light, to thereby adjust the gain.
In this case further, the information recording medium may be shaped in a disc, and the error signal may be at least one of a tracking error signal indicative of a deviation from the record track in a radial direction of the information recording medium at the irradiation position and a focus error signal indicative of a deviation from the record track in a direction perpendicular to the information recording medium at the irradiation position.
By constructing in this way, in case of reproducing or recording the information from or onto the information recording medium shaped in a disc e.g., an optical disc, it is possible to more precisely grasp the change in the gain to be adjusted due to the aged change in the characteristic of the reflection light, to thereby adjust the gain.
Alternatively in this case further, the information recording medium may be shaped in a disc, and the error signal may be at least one of (i) a first gain signal which indicates a gain in a tracking servo control using a tracking error signal indicative of a deviation from the record track in a radial direction of the information recording medium at the irradiation position and (ii) a second gain signal which indicates a gain in a focus servo control using a focus error signal indicative of a deviation from the record track in a direction perpendicular to the information recording medium at the irradiation position.
By constructing in this way, in case of reproducing or recording the information from or onto the information recording medium shaped in a disc e.g., an optical disc, it is possible to more precisely grasp the change in the gain to be adjusted due to the aged change in the characteristic of the reflection light, to thereby adjust the gain.
The above object of the present invention can be also achieved by an information reproducing method including (i) the above described gain controlling method of the present invention (including its various aspects), (ii) an optical pickup process of irradiating the light beam onto the information recording medium and receiving the reflection light to thereby output the light detection signal, (iii) a signal generating process of generating the generation signal on the basis of the light detection signal outputted by the optical pickup process, and (iv) a reproduction controlling process of controlling a reproduction of the information in accordance with the generation signal, the gain of which is roughly and finely adjusted.
According to the information reproducing method of the present invention, it is possible to speedily reproduce the information from the information recording medium while shortening the time duration required for the gain control for the generation signal.
The above object of the present invention can be also achieved by an information recording method including (i) the above described gain controlling method of the present invention (including its various aspects), (ii) an optical pickup process of irradiating the light beam onto the information recording medium and receiving the reflection light to thereby output the light detection signal, (iii) a signal generating process of generating the generation signal on the basis of the light detection signal outputted by the optical pickup process, (iv) a reproducing process of reproducing the information from the information recording medium on the basis of the generation signal, the gain of which is roughly and finely adjusted, and (v) a recording process of processing record information, which is to be recorded onto the information recording medium, on the basis of the reproduced information and recording the processed record information onto the information recording medium.
According to the information recording method of the present invention, it is possible to speedily record the information onto the information recording medium while shortening the time duration required for the gain control for the generation signal.
The nature, utility, and further features of this invention will be more clearly apparent from the following detailed description with respect to preferred embodiments of the invention when read in conjunction with the accompanying drawings briefly described below.